Process of deoxidating metals.



UNITED STATES PATENT OFFICE.

EMIL EHRENSBERGER, or ESSEN, GERMANY, ASSIGNOR TO FRIED. .KRUPP, or SAME PLACE.

PROCESS OF DEOXIDATING METALS.

SPECIFICATION forming part Of Letters Patent 660,846, dated October 30, 1900,

' Application filed June 10, 1896. Serial No. 696,044. (No specimens.)

T at whom it may concern:

Be it known that I, EMIL EHRENSBERGER, a citizen of the German Empire, residing at Essen, Germany, have invented new and useful Improvements in Processes of Deoxidating Metals, (for which I have obtained Letters Patent in Germany, No. 86,607, dated March 5, 1895; in Austria, No. 46/116, dated January 11, 1895; in France, No. 246,073, In dated March 25,1895; in Belgium,No.114,904, dated Agril 3,1895, and in England, No. 6,323, dated March 27, 1895,) of which the following is a specification.

My invention has reference to a process for the removal of oxygen from molten metals such as steel, ingot-iron, nickel-steel, &;c. p which contain oxygen in consequence of their modes of production, and has for its object to provide for such removal of oxygen in a simple :0 and practical manner without otherwise af-' fecting the the inherent qualities of metal or alloy treated. It is well known that the oxygen combines, unless it is prevented from so doing, with the carbon, which is always present in the cast metal, to form carbonic oxid and that this combining action takes place rather slowly and even during the setting or solidification of the cast metal, so that blow-holes are liable to be formed in the metal. Heretofore attempts have been made to obviate this drawback by adding to the metal during the casting or pouringthereof aluminium, either in a pure state or in the form of aluminium -iron. or aluminium -steel. The 3 5 oxygen having a greater chemical afifinity for aluminium than for carbon and iron or for the other metals contained in the casting, combined with the aluminium to form therewith alumina in the shape of a fine powder, which 0 remains for the greater part in suspension in the solidifying mass. Although the formation of blow-holes is prevented by this process, the alumina forms an objectionable impurity in the metal casting. I have found 5 that the oxygen can be removed and the formation of an impurity in the iron or steel prevented by adding to the metal while in a molten condition, either during casting or before the same, instead of aluminium aloneor its alloy with iron an alloy consisting of one or more metals, such as aluminium or manganese, having a greater chemical affinity for oxygen than the metals to be cast and one or more electronegative non-metallic elements or metalloids, such as silicon or boron. The elements of this alloy are converted by tak ing up the oxygen from the casting into single, double, or multiple silicates, borates, &c., which produce a readily-fusible slag. This slag isvery quickly formed, then rises in the form of g] bules upwardly through the liquid and much heavier material of the casting, and renders the. latter perfectly pure and free from blow-holes.

I will now describe a process for the treat 6 ment of basic steel castings.

An alloy of aluminium, manganese, silicon, and iron, in which the manganese and silicon are in the forin of ferromanganese and ferrosilicon, is first prepared, the proportion of 7c the elements in the finished alloy being five per cent.alu1ninium,ten per cent. manganese, ten per cent. silicon, and seventyfive per cent. iron. This alloy is added to the molten steel in such proportions that practically only a trace of the constituent of the same, or at least less than one-tenth of one per cent, remains in the finished casting, it being of course understood that the iron added by the alloy is in such proportion that more or less of the same is not oxidized and remains in the finished casting,while the remaining elements of the alloy are practically completely oxidized and form a readily-fusible slag. The actual quantity of the alloy added to the molten iron or steel will of course depend on the amount of oxygen found to be contained in the iron or steel. Under ordinary conditions from 0.5 to 0.8 per cent. of the alloy is added in the treatment of basic steel.

The addition to the molten metal for the deoxidation or reduction of steel or iron castings may consist simply of a single metal hav- "ing a greater affinity for oxygen than the metal under treatment, such as aluminium, 5 combined with a non-metallic slag-forming substance, such as silicon; but it is generally of advantage to employ at least two metals as an addition, in order to produce double or multiple silicates, which form a much less re- IOO fractory slag than the single silicate does. For this reason I have made use in the above example of the treatment bf steel of two metalsto'wit, aluminium and manganese. If the manganese be omitted from the alloy above set t'orth,- it is still probable that a double salt consisting of aluminium-iron silicate will be formed. However, the presence of manganese positively insures the formation of a readily-fusible slag. In place of aluminium, a metal of the earth, such as magnesium, may he used, or a metal of the alkalies-such as potassium, sodium, &c.may be substituted. Although it is well known that potassium and sodium have a strong atfinity for oxygen their use is not advisable, as the intensity with which they combine with oxygen is very liable to cause explosions. Furthermore, their higher price is an objection to their use. As a non-metallic element boron may be used in place of silicon, it proving to be just assuitable in some cases, and, in fact, more suitable in many cases, as the box-ates formed volatilize at comparatively low temperatures and escape from the molten metal in the form of a vapor immediately after their production. The use of phosphorus and other similar elements in place of boron or silicon is not excluded, as the essen tial objectof using the non-metallic addition is based on the fact that by their absorption of the oxygen contained in the casting they form, with the metals added to them in the alloy, readily fusible or volatile salts, and thereby prevent the formation of pulverulent precipitates.

It will readily be understood from the foregoing that by the addition of a charge containing a metal possessing greater affinity for the oxygen than the molten metal and a nonmetallic element, as described, in proper proportion to the molten metal, all the oxygen is removed from the molten metal and a slag is formed which readily separates from the molten mass and leaves the iron or steel with scarcely a trace of the component parts of the alloy, so that the intrinsic qualities of the metal are not changed or affected.

That I claim as new is-v 1. The herein-described process of removing oxygen from molten iron or steel, or from alloys thereof,consisting in adding to the molten metal an alloy containing a metal having a greater chemical affinity for oxygen than the metal to be treated, and a non-metallic elementthe oxygen compound of which is an acid which combines with the basic oxygen com pound of the metallic element of the alloy to form a fusible slag readily separating from the molten metal, and the alloy being added to the molten metal in such proportions that practically only a trace of the constituents of the same or at least less than 0.1 per cent., remains in the finished casting.

2. The herein-described process of removing oxygen from molten iron or steel, or from alloys thereof,consisting in adding to the molten metal an iron alloy containing a plurality of metals having a greater chemical affinity for oxygen than the metal to be treated, and a non-metallic element the oxygen compound of which is an acid which combines with the basic oxygen compounds of the metallic elements of the alloy to form a fusible slag readily separating from the molten metal, and the alloy being added to the molten metal in such proportions that, with the exception of the iron added, practically only a trace of the constituents of the alloy, or at least less than 0.1 per cent., remains in the finished casting.

3. The herein-described process of removing oxygen from molten iron or steel, or from alloys thereof,consisting in adding to the molten metal an alloy containing aluminium, which has a greater affinity for oxygen than the metal to be treated, and silicon; said constituents of the alloy being so proportioned that the compound formed by the two constituents with the oxygen of the molten metal is a fusible slag readily separating from the molten metal, and the alloy being added to the molten metal in such proportions that practically onlya trace of the constituents of the same, or at least less than 0.1 per cent., remains in the finished casting.

4. The herein'described process of removing oxygen from molten iron or steel or from alloys thereof,consisting in adding to the molten metal an alloy of aluminium, manganese, silicon and iron in the proportion of about five per cent. aluminium, ten percent. manganese, ten per cent. silicon, and seventy-five per cent. iron; said alloy being added To the molten metal in the proportion of about 0.5 per cent. to 0.8 per cent.; whereby the constituents of the compound are oxidized and form a fusible, readily-removable slag, and the finished casting contains-with the exception of the iron added-only a trace, or at least less than 0.1 per cent., of the constituents of the alloy.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

EMIL EHRENSBERGER.

Witnesses:

ALBERT SOHMITZ, ALBERT KLINGHAMMER.

IIO 

